The U.S. general killed in Afghanistan in a suspected insider attack has been identified as Maj. Gen. Harold Greene.

Pentagon officials earlier Tuesday said a U.S. general was killed and 15 other people wounded when a man wearing an Afghan military uniform opened fire at Afghanistan’s military academy in Kabul.

Pentagon spokesman Rear Adm. John Kirby told reporters the assailant was believed to be an Afghan soldier who began firing when the general and other NATO coalition members were visiting Marshal Fahim National Defense University. The shooter was killed in the attack, he said, though did not provide details.

Kirby said he believed the general may have been the highest-ranking American military member to die in the war in Afghanistan.

Kirby said the 15 others wounded included Americans and coalition members from other countries. One was reported to be a German brigadier general.

So-called “green on blue” or “insider” attacks against coalition troops by people dressed as Afghan security forces reached a peak in 2012. Kirby said they remain a threat, but are not indicative of the overall situation in the country.

“The insider threat is a pernicious threat,” he said. “Afghanistan is still a war zone. It’s impossible to completely eliminate that threat.”

Thomas W. O’Connell, a former assistant secretary of defense under the Bush administration, told TheBlaze that the most coalition forces can do is to try to mitigate the threat of such attacks.

“We had fraggings in Vietnam,” O’Connell said. “We had a doctor kill fellow troops at Fort Hood. A suicide-bent idiot is very difficult to identify and stop. If a traitor decides to make the ultimate statement, he will likely succeed.”

He said that monitoring the “behavior and traits of a culture alien to ours is difficult.”

“Some of them must be trusted as a matter of course and we will fail sometimes with those picks,” O’Connell said. “It is the natural course of events when working with allies.”

McConnell said there are some screening technologies that may help prevent some such incidents, but even if NATO had “check weapons” stations at its facilities, troops would still be exposed to green on blue threats outside the wire and at checkpoints within the country manned by Afghan security forces.

This post has been updated.

Editor’s note: ISAF initially incorrectly said the incident took place at Camp Qargha in Kabul.